Abstract: A method of designing a rotor for a horizontal axis wind turbine. The method combines an actuator disk analysis with a cascade fan design method to define the blade characteristics, including the shape and size of the blades, such that the maximum amount of energy is extracted from the air at the lowest rotational speed. A method of manufacturing a wind turbine and a turbine designed in accordance with the method are also disclosed.

Abstract: A fluid turbine for extraction of power from a moving fluid, and that is particularly suitable for use as a wind turbine. The fluid turbine includes, for example, a rotor mounted to a support structure for rotation about a horizontal axis, the rotor having multiple blades extending forwardly and outwardly from a hub, and may include a ring fairing secured to the blades at their outer ends and rotatable with the blades about the axis. The ring fairing may be cocentric with the axis of rotation and may have, at at least one peripheral location thereon, a radial cross-section shaped to develop in operation a circulatory flow about the cross section in such a direction as to increase the velocity of fluid flow between the ring fairing and said hub. In one preferred embodiment of the turbine, the ring fairing cross-sectional shape is an airfoil-section, with a chamber line that is concave outward and forward. Alternatively, the ring faking cross-sectional shape is arcuate, being concave outward and forward.

Abstract: The invention provides a fluid turbine for extraction of power from a moving fluid, and that is particularly suitable for use as a wind turbine. The fluid turbine 30 includes a rotor 32 mounted to a support structure 31 for rotation about a horizontal axis 39, the rotor having multiple blades 37 extending forwardly and outwardly from a hub 36, and a ring fairing 38 secured to the blades at their outer ends and rotatable with the blades about the axis. The ring fairing is concentric with the axis of rotation and has, at at least one peripheral location thereon, a radial cross-section shaped to develop in operation a circulatory flow 60 about the cross section in such a direction as to increase the velocity of fluid flow between the ring fairing and said hub. In one preferred embodiment of the turbine, the ring fairing cross-sectional shape is an airfoil-section 40, with a camber line 55 that is concave outward and forward.